The present invention relates to an ultrasound imaging apparatus which has different types of ultrasound transducers or probes, each with a large number of transducer elements arranged in a predetermined pattern, and which is used by selectively switching the transducers.
In a conventional ultrasound imaging apparatus employing linear electronic scanning, a large number of linearly aligned transducer elements are used and ultrasound transmitting and receiving timings of the ultrasound transducers are controlled to perform linear scanning. Among conventional linear electronic scanning type ultrasound imaging apparatuses, some medical diagnostic ultrasound imaging apparatuses are arranged in the following manner. A plurality of ultrasound probes, normally two probes, are simultaneously connected to each apparatus, and electrical connections to the ultrasound transducers are switched inside the apparatus by a switching circuit consisting of relays or semiconductor switches, thereby using one of the ultrasound transducers to transmit/receive ultrasound waves.
An example of an ultrasound transducer switching circuit is illustrated in FIG. 1.
The switching circuit in FIG. 1 comprises switch section S consisting of switches SWA1 to SWAN and SWB1 to SWBN constituted by relays or semiconductor switches. One terminal of each of switches SWA1 to SWAN is connected to a corresponding one of channels CH1 to CHN for a transmitting and receiving system (including the transmitting and receiving circuits) in the apparatus. One terminal of each of switches SWB1 to SWBN is connected to corresponding one terminal of each of switches SWA1 to SWAN. The other terminal of each of switches SWAl to SWAN is connected to N-channel first connector CA. The other terminal of each of switches SWB1 to SWBN is connected to N-channel second connector CB. Connectors CA and CB are respectively connected to first and second transducers (not shown in FIG. 1) each having a maximum of N transducer elements. Switch section S is controlled by a control circuit arranged in the apparatus to selectively connect the transmitting and receiving system channels CH1 to CHN to connector CA or CB. Upon operation of switch section S, one of the first and second ultrasound probes connected to connectors CA and CB is used to transmit or receive the ultrasound wave.
Switching control in the switching circuit of FIG. 1 can be achieved by selecting one set of switches SWA1 to SWAN and SWB1 to SWBN. For this reason, a maximum number of ultrasound elements in the first or second ultrasound transducer is equal to N, i.e., the number of channels. The width of the field of view and the quality of an ultrasound image produced by the conventional apparatus are limited by the maximum number of first or second ultrasound transducers.